79ⅹ1.8+79ⅹ3.4+21ⅹ5.2=79ⅹ(1.8+3.4)+21ⅹ5.2=79ⅹ5.2+21ⅹ5.2=(79+21)ⅹ5.2=100ⅹ5.2520
79ⅹ1.8+79ⅹ3.4+21ⅹ5.2=79ⅹ(1.8+3.4)+21ⅹ5.2=79ⅹ5.2+21ⅹ5.2=(79+21)ⅹ5.2=100ⅹ5.2=520